SOLUTION: Prove the identity: {{{csc(x)+cot(x)=sin(x)/(1-cos(x))}}}

Algebra ->  Trigonometry-basics -> SOLUTION: Prove the identity: {{{csc(x)+cot(x)=sin(x)/(1-cos(x))}}}      Log On


   



Question 148632: Prove the identity:
csc%28x%29%2Bcot%28x%29=sin%28x%29%2F%281-cos%28x%29%29

Answer by Edwin McCravy(20059) About Me  (Show Source):
You can put this solution on YOUR website!
Prove the identity:
csc%28x%29%2Bcot%28x%29=sin%28x%29%2F%281-cos%28x%29%29

Replace csc%28x%29 on left side by 1%2F%28sin%28x%29%29
Replace cot%28x%29 on left side by %28cos%28x%29%29%2F%28sin%28x%29%29

1%2F%28sin%28x%29%29%2B%28cos%28x%29%29%2F%28sin%28x%29%29

Combine the numerators over the common denominator:

%281%2Bcos%28x%29%29%2F%28sin%28x%29%29

Form the conjugate of the numerator by changing the sign
of the second term:  1-cos%28x%29, put it over itself,
like this %281-cos%28x%29%29%2F%281-cos%28x%29%29, which equals 1,
so we can multiply by it without changing the value:

%28%281%2Bcos%28x%29%29%2F%28sin%28x%29%29%29%28%281-cos%28x%29%29%2F%281-cos%28x%29%29%29

Indicate the multiplications of the tops and bottoms:

%28%281%2Bcos%28x%29%29%281-cos%28x%29%29%29%2F%28sin%28x%29%281-cos%28x%29%29%29%29

FOIL out the top:

+%28++1-cos%28x%29%2Bcos%28x%29-Cos%5E2x+%29%2F%28+sin%28x%29%281-cos%28x%29%29%29+

Simplify by canceling in the top:



+%28++1-Cos%5E2x+%29%2F%28+sin%28x%29%281-cos%28x%29%29%29+

Replace 1-Cos%5E2x by Sin%5E2x

+%28++Sin%5E2x+%29%2F%28+sin%28x%29%281-cos%28x%29%29%29+

The sin%28x%29 in the bottom cancels out the
square in the top:

+%28++Sin%5Ecross%282%29%28x%29+%29%2F%28+cross%28sin%28x%29%29%281-cos%28x%29%29%29+

sin%28x%29%2F%281-cos%28x%29%29

Edwin